One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,7,8,5)(9,10,13,16)(11,14,17,21)(12,19,20,15)(18,24,23,22)(25,26,32,27,31,34,30,35)(28,38,33,39,37,29,40,36)(1,3,4,8)(2,5,6,7)(11,17)(12,20)(14,21)(15,19)(25,27,31,35)(26,30,34,32)(28,39,37,36)(29,33,38,40)(2,6)(5,7)(9,11,13,17)(10,14,16,21)(12,18,20,23)(15,22,19,24)(25,28)(26,29)(27,36)(30,40)(31,37)(32,33)(34,38)(35,39)(3,8)(5,7)(11,17)(14,21)(18,23)(22,24)(25,29,32,36,31,38,30,39)(26,33,27,37,34,40,35,28)(9,12,13,20)(10,15,16,19)(11,18,17,23)(14,22,21,24)(26,34)(27,35)(28,37)(33,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.